01-001 Department of Agriculture, Conservation and Forestry s4

01-001 DEPARTMENT OF AGRICULTURE, CONSERVATION AND FORESTRY

DIVISION OF ANIMAL AND PLANT HEALTH

Chapter 273: CRITERIA FOR LISTING INVASIVE TERRESTRIAL PLANTS

SUMMARY: This chapter establishes criteria to be used in evaluating non-native terrestrial invasive plants that could have adverse economic and/or ecological impacts in Maine. This chapter also establishes the list of evaluated plants that meet the criteria and the restrictions on the distribution and sale of those plants.

I. Definitions

A. Biological potential - The ability of a species to increase its numbers, either sexually and/or asexually.

B. Invasive plant - A non-native species that has spread into native or minimally managed plant communities (habitats) in Maine that causes economic or environmental harm by developing self-sustaining populations and becoming dominant and/or disruptive to native species.

C. Likely invasive plant - A non-native species that is naturalized in Maine, is not yet widespread, but has been found to be invasive in other states or provinces with similar climates.

D. Minimally managed habitats - Minimally managed habitats are habitats where management efforts and investments of time, money and labor are infrequent or nonexistent. These habitats may at one time have been intensively managed.

E. Native Plant - A species that has developed over hundreds or thousands of years in a particular region or ecosystem. Only plants found in this country before European settlement are considered to be native to the United States.

F. Naturalized Plant - A non-native plant that does not need human help to reproduce and maintain itself over time in an area where it is not native.

G. Non-native Plant - A species that is not native or naturally occurring (based on its biology, phylogeny, distribution and current knowledge of the species) within Maine. A species may be native to North America, but non-native in Maine. Non-native is synonymous with non-indigenous, exotic or alien.

H. Potentially invasive plant - Non-native species not currently known to be naturalized in Maine, but that can be expected to become invasive within minimally managed habitats within the state.

I. Spatial gaps - This term is used in reference to the ability of a species to disperse away from existing occurrences. The concept of crossing spatial gaps is used to describe those 01-001 Chapter 273 page 2

species that can disperse over discontinuities and become established elsewhere. This contrasts to other species that spread across a habitat only by continual, uninterrupted growth.

J. Species - As utilized in this chapter, "species" includes all synonyms, subspecies, hybrids, varieties, forms and cultivars of that species unless proven otherwise by a process of scientific evaluation.

II. Criteria for Evaluating Terrestrial Plant Species

In order to include a plant on a list of invasive terrestrial plant species administered by the Maine Department of Agriculture, Conservation and Forestry the following criteria must be met:

A. All of the following criteria must be met for a terrestrial plant species to be considered either invasive, likely invasive or potentially invasive. The species must:

1. Be non-native to Maine.

2. Have the potential for rapid growth, dissemination and establishment in minimally managed habitats.

3. Have the biological potential for widespread dispersion and for dispersing over spatial gaps.

4. Have the biological potential for existing in high numbers or large colonies in minimally managed habitats.

5. Have the potential to displace native species in minimally managed habitats.

B. All of the following criteria must be met for a terrestrial plant species to be considered invasive. The species must:

1. Be widespread in a region or habitat type(s) in Maine.

2. Have many occurrences of numerous individuals or colonies that displace native species in minimally managed habitats in Maine.

C. All of the following criteria must be met for a terrestrial plant species to be considered likely invasive. The species must:

1. Be naturalized in Maine (persist without cultivation).

2. Have at least one occurrence in Maine that has high numbers of individuals forming dense stands in minimally managed habitat, or have demonstrated to be invasive in nearby states and provinces or areas with similar climates, but its status in Maine is unknown or unclear. Unknown status may result from lack of field experience with the species or from difficulty in species determination or taxonomy. 01-001 Chapter 273 page 3

D. All of the following criteria must be met for a terrestrial plant species to be considered potentially invasive. The species must:

1. Have no known naturalized occurrences in Maine.

2. Have demonstrated to be invasive in nearby states and provinces or areas with similar climates.

3. Be anticipated to naturalize in Maine.

III. List of Invasive Terrestrial Plant Species

Plant species that have been evaluated and meet the criteria for one of the categories listed in section II.

Scientific name Common name Evaluation Criteria Acer platanoides Norway Maple Invasive Alliaria petiolata Garlic Mustard Invasive Berberis thunbergii Japanese Barberry Invasive Celastrus orbiculatus Asiatic Bittersweet Invasive Elaeagnus umbellata Autumn Olive Invasive Euonymus alatus Winged Euonymus Invasive Fallopia japonica Japanese Knotweed Invasive Frangula alnus Glossy buckthorn Invasive Hesperius matronalis Dame’s Rocket Invasive Iris pseudacorus Yellow Iris Invasive Lonicera morrowii Morrow’s Honeysuckle Invasive Lonicera tatarica Tartarian Honeysuckle Invasive Lythrum salicaria Purple Loosestrife Invasive Robinia pseudoacacia Black Locust Invasive Rosa multiflora Multiflora Rose Invasive Acer ginnala Amur Maple Likely Invasive Aegopodium podagraria Bishop’s Weed Likely Invasive Ailanthus altissima Tree of Heaven Likely Invasive Amorpha fruticosa False Indigo Bush Likely Invasive Artemisia vulgaris Common Mugwort Likely Invasive Berberis vulgaris Common Barberry Likely Invasive Euphorbia cyparissias Cypress Spurge Likely Invasive Ligustrum vulgare Common Privet Likely Invasive Lonicera japonica Japanese Honeysuckle Likely Invasive Lonicera maackii Amur or Bush Honeysuckle Likely Invasive Populus alba White Cottonwood Likely Invasive Impatiens glandulifera Ornamental Jewelweed Likely Invasive Ampelopsis glandulosa Porcelain Berry Potentially Invasive Fallopia baldschuanica Chinese Bindweed Potentially Invasive 01-001 Chapter 273 page 4

Microstegium vimineum Japanese Stilt Grass Potentially Invasive Paulownia tomentosa Paulownia Potentially Invasive Persicaria perfoliata Mile a Minute Weed Potentially Invasive Phellodendron amurense Amur Cork Tree Potentially Invasive

IV. Prohibitions and restrictions

No person shall import, export, buy, sell, or intentionally propagate for sale or distribution any living and viable portion of any plant species, which includes all of their cultivars, varieties and hybrids, listed in Section III as invasive, likely invasive or potentially invasive.

V. Transition

Plants listed in Section III that are already growing in Maine or in the channels of trade in Maine at the time this rule is adopted will be exempt from Section IV until December 31, 2017.

VI. Variances

A A variance may be granted by the State Horticulturist to allow for importation and field experimentation of invasive plants listed in Section III for scientific, educational, or other purposes under conditions prescribed by the State Horticulturist. Any variance(s) shall be in the form of a permit issued by the State Horticulturist.

B Preserved specimens in the form of herbaria or other preservation means are exempt from this rule.

C Varieties, cultivars, hybrids and/or subspecies that have been shown not to be invasive through peer reviewed scientific research and analysis may be considered exempt from this rule after review by a committee established by the Department.

VII. Periodic Review

The plant list in Section III will be reviewed and amended on a five year basis unless a person petitions the Department with significant scientific research and analysis that, in the Department’s determination, warrants review for possible amendment to the list at an earlier date. 01-001 Chapter 273 page 5

STATUTORY AUTHORITY: 7 M.R.S.A. Chapter 405-A Section 2211

EFFECTIVE DATE: December 25, 2011 – filing 2011-469

CORRECTIONS: February, 2014 – agency names, formatting

AMENDED: January 14, 2017 – filing 2017-003